A necessary condition for justifying a policy such as publicly provided or subsidized low-incomehousing is that it has a real effect on recipients’ outcomes. In this paper, we examine one aspect of thereal effect of public or subsidized housing -- does it increase the housing stock? If subsidized housingraises the quantity of occupied housing per capita, either more people are finding housing or they arebeing housed less densely. On the other hand, if public or subsidized housing merely crowds outequivalent-quality low-income housing that otherwise would have been provided by the private sector,the housing policy may have little real effect on housing consumption. Using Census place-level datafrom the decennial census and from the Department of Housing and Urban Development, we ask whether places with more public and subsidized housing also have more total housing, after accounting for housing demand. We find that government-financed units raise the total number of units in a Censusplace, although on average three government-subsidized units displace two units that would otherwisehave been provided by the private market. There is less crowd out in more populous markets, and morecrowd out in places where there is less excess demand for public housing, as measured by the number of government-financed units per eligible person. Tenant-based housing programs, such as Section 8Certificates and Vouchers, seem to be more effective than project-based programs at targeting subsidizedhousing units to people who otherwise would not have their own.Todd Sinai Joel WaldfogelThe Wharton School The Wharton SchoolUniversity of Pennsylvania University of Pennsylvania308 Lauder-Fischer Hall 3113 Steinberg Hall-Dietrich Hall256 South 37th Street 3620 Locust Walk Philadelphia, PA 19104-6330 Philadelphia, PA 19104-6372and NBER and NBER (215) 898-5390 (215) 898-7148sinai@wharton.upenn.edu waldfogj@wharton.upenn.edu

1Through various levels of government, the U.S. spends a considerable sum subsidizing housing,as much as $25 billion in budget outlays on an annualized basis. [Quigley (2000)] These subsidiesinclude both direct provision of housing services through public housing, and voucher programs that aimto shoulder a portion of the cost of privately provided housing, such as Section 8 housing assistance.The implicit rationale underlying both of these programs is that, in the absence of governmentintervention, poor people would consume inadequate amounts of housing, either because the marketwould deliver too little that was sufficiently affordable or poor people would choose to consume toomuch other goods. [Olsen (2001)]In spite of the large expenditures on these programs, it is far from obvious whether they haveany effect on whether families have their own housing units. It is possible, instead, that these programssimply transfer resources to families that would be housed even in the programs’ absence. If so, onemight regard the programs as wasteful and ineffectual, although such a conclusion would not necessarilyfollow as subsidies might allow households to occupy better housing units. In this paper we ask whetherlow-income housing subsidies satisfy a simple sufficient condition for effectuality: do they increase thenumber of families housed in their own units or do they simply crowd-out privately-provided low-income housing? In particular, if subsidized housing raises the quantity of occupied housing units percapita, either more people are finding housing or they are being housed less densely.Using cross-sectional data on total housing, subsidized housing, and population (and otherdemand shifters) in 22,901 Census designated places, we find neither complete crowd out, nor thatsubsidized housing is all net new. We estimate that an additional subsidized unit raises the total numberof units in a place by between 0.25 and 0.375 units. Lending credibility to the estimates, we find that